20409218 has 4 divisors (see below), whose sum is σ = 30613830. Its totient is φ = 10204608.

The previous prime is 20409217. The next prime is 20409223. The reversal of 20409218 is 81290402.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 20403289 + 5929 = 4517^2 + 77^2 .

It is not an unprimeable number, because it can be changed into a prime (20409217) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5102303 + ... + 5102306.

Almost surely, 2^20409218 is an apocalyptic number.

20409218 is a deficient number, since it is larger than the sum of its proper divisors (10204612).

20409218 is a wasteful number, since it uses less digits than its factorization.

20409218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10204611.

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 20409218 is about 4517.6562507566. The cubic root of 20409218 is about 273.2805909868.

The spelling of 20409218 in words is "twenty million, four hundred nine thousand, two hundred eighteen".